BTLA and graft versus host disease: We therefore immunized C57BL/6 and BXD75 mice with HDM and seven days later challenged with HDM, concurrently with 100 μg BTLA agonist (clone 6A6) i.p., previously reported to attenuate Graft-versus-host-disease (GVHD), or isotype control (Figure 5A) (39).